Engineering long-range interactions between ultracold atoms with light

Ultracold temperatures in dilute quantum gases opened the way to an exquisite control of matter at the quantum level. Here we focus on the control of ultracold atomic collisions using a laser to engineer their interactions at large interatomic distances. We show that the entrance channel of two colliding ultracold atoms can be coupled to a repulsive collisional channel by the laser light so that the overall interaction between the two atoms becomes repulsive: this prevents them to come close together and to undergo inelastic processes, thus protecting the atomic gases from unwanted losses. We illustrate such an optical shielding mechanism with 39K and 133Cs atoms colliding at ultracold temperature (<1 microkelvin). The process is described in the framework of the dressed-state picture and we then solve the resulting stationary coupled Schrödinger equations. The role of spontaneous emission and photoinduced inelastic scattering is also investigated as possible limitations of the shielding efficiency. We predict an almost complete suppression of inelastic collisions over a broad range of Rabi frequencies and detunings from the 39K D2 line of the optical shielding laser, both within the [0, 200 MHz] interval. We found that the polarization of the shielding laser has a minor influence on this efficiency. This proposal could easily be formulated for other bialkali-metal pairs as their long-range interaction are all very similar to each other.

The Growth Kinetics of RhizoctoniasolaniAfter 1 MeV Electron Irradiation

Crops, especially potatoes, are prone to a wide range of fungal, viral and bacterial diseases, including black scurf caused by Rhizoctoniasolani. This study focused on the radiation treatment of the phytopathogenic fungus RhizoctoniasolaniKuhn, grown from sclerotium irradiated with 1 MeV electrons in the dose range from 20 to 4500 Gy. The doses absorbed by the sclerotia were determined using computer simulation. The growth of the fungus samples was monitored after 24, 48, 72, and 96 hours from the time of seeding. It was found that the dependence of the radial growth velocity of R. solani on the time after irradiation with doses ranging from 20to 1800 Gywas nonlinear. Irradiation at a dose over 4500 Gyled to complete suppression of the germination of R. solani sclerotia. Keywords: radiation treatment, electron radiation, radiation dose, sclerotia of Rhizoctoniasolani, Kuhn, radial velocity of growth

Data fusion and 3D visualization for optimized representation of neurovascular relationships in the posterior fossa

Background Reliable 3D visualization of neurovascular relationships in the posterior fossa at the surface of the brainstem is still critical due to artifacts of imaging. To assess neurovascular compression syndromes more reliably, a new approach of 3D visualization based on registration and fusion of high-resolution MR data is presented. Methods A total of 80 patients received MRI data with 3D-CISS and 3D-TOF at 3.0 Tesla. After registration and subsequent segmentation, the vascular information of the TOF data was fused into the CISS data. Two 3D visualizations were created for each patient, one before and one after fusion, which were verified with the intraoperative situation during microvascular decompression (MVD). The reproduction quality of vessels was evaluated with a rating system. Results In all cases, the presented approach compensated for typical limitations in the 3D visualization of neurovascular compression such as the partial or complete suppression of larger vessels, suppression of smaller vessels at the CSF margin, and artifacts from heart pulsation. In more than 95% of the cases of hemifacial spasm and glossopharyngeal neuralgia, accurate assessment of the compression was only possible after registration and fusion. In more than 50% of the cases with trigeminal neuralgia, the presented approach was crucial to finding the actually offending vessel. Conclusions 3D visualization of fused image data allows for a more complete representation of the vessel-nerve situation. The results from this approach are reproducible and the assessment of neurovascular compression is safer. It is a powerful tool for planning MVD.

Superconductor-insulator transitions in three-dimensional indium-oxide at high pressures

Experiments investigating magnetic-field-tuned superconductor-insulator transition (HSIT) mostly focus on two-dimensional material systems where the transition and its proximate ground-state phases, often exhibit features that are seemingly at odds with the expected behavior. Here we present a complementary study of a three-dimensional pressure-packed amorphous indium-oxide (InOx) powder where granularity controls the HSIT. Above a low threshold pressure of ~0.2 GPa, vestiges of superconductivity are detected, although neither a true superconducting transition nor insulating behavior are observed. Instead, a saturation at very high resistivity at low pressure is followed by saturation at very low resistivity at higher pressure. We identify both as different manifestations of anomalous metallic phases dominated by superconducting fluctuations. By analogy with previous identification of the low resistance saturation as a "failed superconductor", our data suggests that the very high resistance saturation is a manifestation of a "failed insulator". Above a threshold pressure of ~6 GPa, the sample becomes fully packed, and superconductivity is robust, with TC tunable with pressure. A quantum critical point at PC~25 GPa marks the complete suppression of superconductivity. For a finite pressure below PC, a magnetic field is shown to induce a HSIT from a true zero-resistance superconducting state to a weakly insulating behavior. Determining the critical field, HC, we show that similar to the 2D behavior, the insulating-like state maintains a superconducting character, which is quenched at higher field, above which the magnetoresistance decreases to its fermionic normal state value.

A dual parallel Mach–Zehnder modulator linearization scheme based on 90° phase shifters

In this paper, a dual-drive dual-parallel Mach–Zehnder Modulator based linearization scheme is implemented by utilizing only two phase shifters and comprehensively demonstrated for a photonic transmission link. Third order intermodulation distortion is suppressed by adjusting angles of electrical phase shifters i.e. π/2 and−π/2 and a non-linear distortion immune system can be proposed for microwave photonic link. A complete suppression in intermodulation terms and 20.8 dB enhancements are found in spurious free dynamic range (SFDR). SFDR reaches 135.6 dB Hz4/5 by suppressing major spurious contributors of third order intermodulation distortions in optical domain only which ensures the improvement in performance of link against non-linear terms.

A Pilot Study of Natural Formulation Activity in the Protection of Stored Wheat and Barley Against the Stored-Product Insects

The stored-product insects are one of the major causes of losses in the stored cereals. Most of control measures still rely on a synthetic pesticide usage, but due to its negative side effects on the goods, human health, and the environment, there is an urgent need for an alternative control. A natural formulation based on the diatomaceous earth (DE) SilicoSec®, enhanced with the botanicals (essential oil lavender, corn oil, and bay leaves dust) and the silica gel was developed. The aim of the study was to test the activity of the developed formulation as a postharvest protectant of seed wheat and barley in the suppression Sitophilus oryzae (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst). As a reference comparative value, the DE SilicoSec® was applied. Subsequent to the six months of storage under the simulated warehouse conditions, the formulation has completely suppressed the initial population development of all three tested insect species, both in wheat and barley. In wheat, a complete suppression was detected at the dose of 500 ppm against T. castaneum and 600 ppm against both R. dominica and S. oryzae. In barley, a complete suppression was detected at the doses of 500 ppm, 400 ppm, and 600 ppm against R. dominica, T. castaneum and S. oryzae, respectively. Conclusively, the results of this study indicate that the developed natural formulation based on the DE, botanicals, and silica gel was highly effective against the three major stored‐product insect species, providing a long-term safe storage of wheat and barley seeds.

Successful ablation of bifocal PVCs from both left bundle branches triggering polymorphic VT in LQTS 2—A case report

Background A 19-year-old woman with an established diagnosis of long QT syndrome (LQTS) 2 and underlying KCNH2-mutation was referred to our centre for recurrent polymorphic ventricular tachycardia (VT) and ventricular fibrillation (VF) refractory to medical therapy and bilateral thoracic sympathectomy. Case summary Holter monitoring revealed a relevant PVC burden of two different morphologies. One PVC was originating from the left anterior fascicle, the other from the left posterior fascicle. Radiofrequency ablation resulted in complete suppression of both spontaneous PVC morphologies with a favourable clinical course over the next 2 years. Discussion This case presents two interesting insights: Firstly, the consistent bigeminal pattern of the torsade de pointes triggering PVC. These were retrieved from the device interrogation and correlated with the pattern that was seen at the time of the procedure. Secondly, PVC morphologies suggested an origin from both the left ventricular (posterior and anterior) fascicles, which has not been described so far. This was confirmed by the preceding Purkinje potentials seen at the successful ablation sites in sinus rhythm and during PVC. Ablation of triggering PVCs causing recurrent VT/VF in LQT 2 syndrome is feasible and effective over a mid-term Follow-up.

Neural correlates and determinants of approach-avoidance conflict in the prelimbic prefrontal cortex

The recollection of environmental cues associated with threat or reward allows animals to select the most appropriate behavioral responses. Neurons in the prelimbic cortex (PL) respond to both threat- and reward-associated cues. However, it remains unknown whether PL regulates threat-avoidance vs. reward-approaching responses when an animals' decision depends on previously associated memories. Using a conflict model in which male Long-Evans rats retrieve memories of shock- and food-paired cues, we observed two distinct phenotypes during conflict: i) rats that continued to press a lever for food (Pressers); and ii) rats that exhibited a complete suppression in food seeking (Non-pressers). Single-unit recordings revealed that increased risk-taking behavior in Pressers is associated with persistent food-cue responses in PL, and reduced spontaneous activity in PL glutamatergic (PLGLUT) neurons during conflict. Activating PLGLUT neurons in Pressers attenuated food-seeking responses in a neutral context, whereas inhibiting PLGLUT neurons in Non-pressers reduced defensive responses and increased food approaching during conflict. Our results establish a causal role for PLGLUT neurons in mediating individual variability in memory-based risky decision making by regulating threat-avoidance vs. reward-approach behaviors.

Spurious free thickness shear bulk acoustic resonators on lithium niobate using standard and broadband piston mode designs

This paper describes design and fabrication of sprious-free thickness shear bulk acoustic resonators (TSBARs) using the lithium niobate (LN) plate. Previously, the authors conjected from the experiment on the TSBAR that cutoff edges with crystal LN X-plane serve as ideal reflectors for the piston mode operation, and complete suppression is possible by adding the standard piston mode design to the other edges normal to the X-axis. Following to this conjecture, the traditional piston mode structure is designed by the traditional two-dimensional finite element method, and the TSBAR is fabricated following to the design. The experiment showed complete suppression of the transverse mode resonances, and the conjecture was verified.